TW201302616A - A method for preparing indium sulfide thin film - Google Patents

Abstract

A method for preparing indium sulfide film is provided. The method includes: providing a mixed solution of a complexing agent, indium ion, and hydrogen sulfide ion; and contacting the mixed solution with a substrate to form a indium sulfide film thereon; wherein the complexing agent has the following formula: wherein each of R1 and R2 respectively is hydrogen or hydroxyl.

Description

Method for preparing indium sulfide film

The present invention relates to the preparation of indium sulfide thin films, and more particularly to a method of forming an indium sulfide thin film by a chemical bath deposition method.

In thin-film solar cells, the buffer layer is a very important part, which can form a p-n junction with the absorption layer to help the electrons to conduct efficiently, so that the light energy can be fully converted into electrical energy.

Since Boeing published chemical bath deposition (CBD) in 1982, chemical bath coating has become a well-known film preparation technology. The advantages of this technology include easy implementation, low equipment cost, excellent coating quality, etc., and therefore are suitable for the preparation of a solar cell buffer layer.

In the chemical bath coating process, two nucleation mechanisms are involved, including homogenous nucleation and heterogeneous nucleation. The anion and cation in the heterogeneous nucleating system solution form a crystal nucleus on the heterogeneous interface, and the nucleus continues to stack chemical reaction through the subsequent ions, and grows and forms a thin film at the hetero interface. Homogeneous nucleation is the formation of a nucleus directly in the liquid, and after the chemical reaction of the subsequent ions to continue stacking, a granular suspension is formed in the solution.

In general, when the chemical bath coating method is applied to the preparation of a solar cell buffer layer material, the reaction is mainly carried out by reacting hydrogen sulfide ions (HS ^- ) and metal ions to form a metal sulfide film deposited on the substrate. Traditionally, since the chemical used to supply the hydrogen sulfide ion is thiourea, it must react with hydroxide (OH ^- ) in an alkaline environment to release the hydrogen sulfide ion into the solution, in an acidic environment. Sulfide ions (S ²⁻ ) are released, so that the buffer layer is prepared by a chemical bath coating method generally in an alkaline environment. However, if the metal ions used are likely to form an insoluble hydroxide precipitate in an alkaline environment, the desired metal sulfide film cannot be prepared by a chemical bath plating method.

The common buffer layer material is cadmium sulfide (CdS), but cadmium is a heavy metal, which is easy to cause harm to people and the environment. Therefore, the development of cadmium-free buffer layer is an important direction for future research and development. Indium sulfide (In ₂ S ₃ ) is a cadmium-free buffer layer material which is currently studied. The preparation method of indium sulfide is, for example, atomic layer deposition (ALD), evaporation, sputtering, or the like. However, most methods for gas phase preparation require harsh conditions such as vacuum and high temperature, which easily destroy the original morphology of the film.

Therefore, there is an urgent need to develop a buffer layer preparation method which is simple in method, low in cost, less toxic and harmful, and can be mass-produced.

An embodiment of the present invention provides a method for preparing an indium sulfide film, comprising: providing a mixed solution containing a binder, indium ions, and hydrogen sulfide ions; and contacting the mixed solution with a substrate to form on the substrate An indium sulfide (In ₂ S ₃ ) film; wherein the compounding agent has the following chemical formula:

Wherein R ₁ and R ₂ are each independently hydrogen or a hydroxyl group.

The above and other objects, features and advantages of the present invention will become more <RTIgt;

Several different embodiments are set forth below in accordance with various features of the invention. The specific elements and arrangements of the present invention are intended to be simplified, but the invention is not limited to these embodiments. For example, a description of forming a first element on a second element can include an embodiment in which the first element is in direct contact with the second element, and also includes having additional elements formed between the first element and the second element such that An embodiment in which one element is not in direct contact with the second element. In addition, the present invention is represented by the repeated reference numerals and/or letters in the different examples for the sake of brevity, but does not represent a particular relationship between the various embodiments and/or structures.

The embodiment of the invention provides a preparation method of an indium sulfide film, which has the advantages of short reaction time, good coating quality, low reaction temperature, simple method, low cost and less toxicity, so the industrial application is good, for example, it can be used as copper indium gallium selenide. (Copper Indium Gallium Diselenide, abbreviated as CIGS) buffer layer of thin film solar cells.

First, a mixed solution containing a binder, indium ions, and hydrogen sulfide ions is provided. For example, a miscible agent may be added first, followed by addition of indium ions and hydrogen sulfide ions. Then, the mixed solution is brought into contact with the substrate, and an indium sulfide (In ₂ S ₃ ) film is formed on the substrate at room temperature or under heating.

The above complexing agent may have the following chemical formula:

Wherein R ₁ and R ₂ independently comprise hydrogen or a hydroxyl group. Specific examples of the complexing agent include tartaric acid, succinic acid, or a combination of the foregoing.

The function of the above-mentioned complexing agent is to sequester the indium ions in the solution with two carboxylic acid groups. In general, when chelation is performed, it is necessary to select an appropriate complexing agent according to the size of the chelate target, and thus the different intercalating agents for different ions are also different. The inventors have found that for indium ions, the carboxylic acid groups on the complexing agent used need to be exactly two carbons apart, so that the distance between the two carboxylic acid groups matches the size of the indium ions, and thus can be combined with indium ions. Have good chelation ability. If there is only one carbon distance between the two carboxylic acid groups of the wrong agent, for example, malonic acid is used as a blocking agent, the indium ions cannot be smoothly sequestered because the distance between the carboxylic acid groups is too small. Conversely, if the two carboxylic acid groups of the wrong agent have a distance of more than two carbons, for example, the wrong agent is citric acid having a distance of three carbons between the two carboxylic acid groups, because the distance between the carboxylic acid groups is too It has a large and freely rotatable range and does not have a good chelating ability for indium ions.

The source of indium ions in the mixed solution can be obtained by adding a metal salt containing indium to the solution, for example, adding indium sulfate, indium chloride, indium acetate, other salts soluble in water to generate indium ions, or the foregoing combination. In addition, the source of the hydrogen sulfide ion in the mixed solution can be obtained by adding thioacetamide to the solution. The pH of the resulting mixed solution may be between 1 and 3. In an embodiment of the invention, the mixed solution having the wrong agent, the indium ion, and the hydrogen sulfide ion has a concentration ratio of the wrong agent, the indium ion, and the hydrogen sulfide ion of 0.01 M to 0.5 M: 0.025 M. ~0.1 M: 0.01 M~1 M, preferably between 0.05 M and 0.15 M: 0.04 M~0.12 M: 0.04 M~0.4 M.

After preparing a mixed solution having a wrong agent, indium ions, and hydrogen sulfide ions, a chemical bath coating method can be used on various substrates (including, but not limited to, Copper Indium Gallium Diselenide (CIGS). A film of indium sulfide is deposited on the substrate). The reaction temperature of the chemical bath coating method is not particularly limited and may generally be between 25 ° C and 80 ° C. The thickness of the indium sulfide film can be adjusted according to actual needs. When used as a buffer layer for a copper indium gallium selenide thin film solar cell, the thickness is generally between 20 and 100 nm.

Figure 1 shows a schematic of a typical copper indium gallium selenide thin film solar cell. As shown in FIG. 1, the thin film solar cell includes a substrate 102 on which a back electrode 104, a copper indium gallium selenide absorber layer 106, an indium sulfide thin film buffer layer 108, and a transparent conductive layer 110 are sequentially disposed. In the above, the substrate 102 is, for example, glass, a polymer substrate, or a metal substrate. Back electrode 104 is, for example, molybdenum. The transparent conductive layer 110 is, for example, a zinc oxide layer.

In a specific embodiment, the substrate 102 on which the back electrode 104 and the copper indium gallium selenide absorbing layer 106 have been formed may be immersed in the aforementioned mixed solution to form an indium sulfide thin film buffer layer 108. The indium sulfide film formed in the embodiment of the invention has a flat and dense surface, and the buffer layer applied to the solar cell can have good reliability of the performance of the battery.

In general, chemical bath coating methods include both homogenous nucleation and heterogeneous nucleation. Therefore, in the formation of an indium sulfide thin film, if the complexing agent has a good chelating ability with the indium ion, for example, the use of the two carboxylic acid groups in the present invention is precisely a two-carbon intercalating agent, which tends to undergo heterogeneous nucleation. A step of. That is, after the hydrogen sulfide ion in the solution is first connected to the indium ion chelated by the wrong agent, the complexing agent is separated from the indium ion. At this time, another hydrogen sulfide ion can be re-attached to the indium ion, and the above steps are repeated. Therefore, in the process of heterogeneous nucleation, the film is formed by stacking one atom at a time, and becomes a short-range ordered long-range disorder state, so the formed indium sulfide film is in an amorphous state. The indium sulfide thin film formed under this condition has a flat surface, and therefore, when used as a buffer layer of a solar thin film battery, it can be joined well to the upper transparent conductive layer without voids.

However, if the chelating ability of the complexing agent with indium ions is not good, for example, a complexing agent in which two carboxylic acid groups are separated by less than or more than two carbons is used, the step of homogenous nucleation tends to proceed. Since the indium ions are not well chelated in the solution when the complexing agent is not well-bonded with the indium ions, the indium ions are rapidly reacted with the sulfur ions in the solution to form indium sulfide. Then, the indium sulfide in the solution is further stacked to form a crystalline indium sulfide film. Such a crystalline indium sulfide film has a needle-like surface. If it is used as a buffer layer of a solar cell, the rough surface thereof causes a lot of voids inside the battery, thereby causing an excessive resistance value.

In addition, when the chelating ability of the complexing agent with indium ions is poor and a large amount of indium ions are present in the solution, the indium ions react with the hydroxide ions in the solution to form a hydroxide precipitate of indium, which cannot form a high purity. Indium sulfide film. Since the hydroxide of indium affects the size of the energy gap, that is, the higher the hydroxide content, the larger the energy gap. Therefore, the indium sulfide film does not match the energy level of the CIGS absorber layer, and the Hetero interface is easily formed, causing structural defects. At this time, the battery penetration is lowered and the resistance value is increased, so that the battery efficiency cannot be optimized. Therefore, in order to avoid the generation of hydroxide when forming an indium sulfide film, it is necessary to add an acid such as hydrochloric acid during the process to neutralize the hydroxide in the solution.

However, since the complexing agent used in the present invention has a good chelating ability with indium ions, a large amount of indium ions do not react with the hydroxide in the solution, so that it is possible to avoid the addition of an additional acid to adjust the pH of the solution. The formation of a high purity indium sulfide thin film can be obtained by the formation of a hydroxide of indium.

[Example 1]

First, tartaric acid is used as a blocking agent, and it is dissolved in deionized water, stirred until completely dissolved, and then indium sulfate (In ₂ (SO ₄ ) ₃ ) which can release indium ions is added, and stirred until completely dissolved. Then, a solution of thioacetamide (SC(NH ₂ )(CH ₃ ))) was added, and the mixture was stirred and mixed uniformly to form a mixed solution having a complexing agent, indium ions, and hydrogen sulfide ions. Among them, the concentration ratio of indium sulfide: tartaric acid: thioacetamide is 0.008 M: 0.1 M: 0.04 M. The above mixed solution was placed in a reaction vessel.

A printed CIGS layer was printed as a substrate, and immersed in a mixed solution having a binder, an indium ion, and a hydrogen sulfide ion in a face down manner, and the reaction vessel was covered. The reaction was carried out for 105 minutes in a water bath at 65 ° C to obtain a yellow indium sulfide film. The coverage of the indium sulfide film on the copper indium gallium selenide layer is greater than 99%, and the film thickness is about 30 nm. Referring to Fig. 2, a secondary electron image (SEI) of the formed indium sulfide thin film is shown.

[Example 2]

First, tartaric acid is used as a blocking agent, and it is dissolved in deionized water, stirred until completely dissolved, and then indium sulfate (In ₂ (SO ₄ ) ₃ ) which can release indium ions is added, and stirred until completely dissolved. Then, a solution of thioacetamide (SC(NH ₂ )(CH ₃ ))) was added, and the mixture was stirred and mixed uniformly to form a mixed solution having a complexing agent, indium ions, and hydrogen sulfide ions. Among them, the concentration ratio of indium sulfide: tartaric acid: thioacetamide is 0.008 M: 0.1 M: 0.24 M. The above mixed solution was placed in a reaction vessel.

A sputtering CIGS layer is sputtered as a substrate, and is immersed in a mixed solution having a dissimilar agent, an indium ion, and a hydrogen sulfide ion in a face down manner, and the reaction container is covered. . The reaction was carried out for 45 minutes in a water bath at 65 ° C to obtain a yellow indium sulfide film. The coverage of the indium sulfide film on the copper indium gallium selenide layer is greater than 99%, and the film thickness thereof is about 50-100 nm. Referring to Fig. 3, a secondary electron image of the formed indium sulfide film is shown.

[Example 3]

First, tartaric acid is used as a blocking agent, and it is dissolved in deionized water, stirred until completely dissolved, and then indium sulfate (In ₂ (SO ₄ ) ₃ ) which can release indium ions is added, and stirred until completely dissolved. Then, a solution of thioacetamide (SC(NH ₂ )(CH ₃ ))) was added, and the mixture was stirred and mixed uniformly to form a mixed solution having a complexing agent, indium ions, and hydrogen sulfide ions. Among them, the concentration ratio of indium sulfide: tartaric acid: thioacetamide is 0.008 M: 0.1 M: 0.4 M. The above mixed solution was placed in a reaction vessel.

A printed CIGS layer was printed as a substrate, and immersed in a mixed solution having a binder, indium ions, and hydrogen sulfide ions in a face down manner, and the reaction vessel was covered. The reaction was carried out for 20 minutes in a water bath at 65 ° C to obtain a yellow indium sulfide film. The coverage of the indium sulfide film on the substrate of CIGS is greater than 99%, and the film thickness is about 20-40 nm. Referring to Fig. 4, a secondary electron image of the formed indium sulfide thin film is shown.

Further, the above-mentioned indium sulfide film was actually used as a buffer layer of the battery, and its battery efficiency was tested. First, copper oxide, gallium oxide, and indium oxide are mixed in a specific ratio (Cu/(In+Ga)=0.85/(0.7+0.3), and nano-oxide particles are formed by ball milling. Then, the aforementioned particles are coated with a doctor blade. after the cloth. then after hydrogen reduction (H ₂ reduction process) after selenide (selenized) to give the CIGS absorber layer is a thin film on a molybdenum / chromium / steel substrate., by the chemical bath deposition film deposited on the indium sulfide absorbent On the layer, ZnO/AZO (aluminum-doped zinc oxide) is sputtered on the indium sulfide layer, and finally the electrode is plated to complete the fabrication of the battery element. The 2×2 square centimeter battery is divided into nine small areas ( The 0.141 cm2 battery (cell1-9) measures the nature of the photovoltaic properties with current-voltage and quantum efficiency.

Fig. 5 shows the results of battery efficiency when an indium sulfide thin film was used as a buffer layer of a CIGS battery. As can be seen from Figure 5, the indium sulfide film can be used as a buffer layer for CIGS cells with good battery efficiency (cell efficiency is about 11%), so it can be used to replace the traditional cadmium sulfide buffer layer to avoid cadmium to the environment. Pollution.

[Embodiment 4]

First, tartaric acid is used as a blocking agent, and it is dissolved in deionized water, stirred until completely dissolved, and then indium sulfate (In ₂ (SO ₄ ) ₃ ) which can release indium ions is added, and stirred until completely dissolved. Then, a solution of thioacetamide (SC(NH ₂ )(CH ₃ ))) was added, and the mixture was stirred and mixed uniformly to form a mixed solution having a complexing agent, indium ions, and hydrogen sulfide ions. Among them, the concentration ratio of indium sulfide: tartaric acid: thioacetamide is 0.008 M: 0.1 M: 0.4 M. The above mixed solution was placed in a reaction vessel.

Molybdenum glass was used as a substrate, and immersed in a mixed solution having a binder, indium ions, and hydrogen sulfide ions in a face down manner, and the reaction vessel was covered. The reaction was carried out for 30 minutes in a water bath at 65 ° C to obtain a yellow indium sulfide film. The coverage of the indium sulfide film on the substrate of the molybdenum glass is greater than 99%, and the film thickness thereof is about 50 to 60 nm. Referring to Fig. 6, a secondary electron image of the formed indium sulfide film is shown.

Fig. 7 is a Raman spectrum of the formed indium sulfide thin film. Since there is no signal of indium and hydroxide bonding and indium oxide in the figure, only the signal of indium sulfide, that is, the formed indium sulfide film is not contaminated by indium hydroxide or oxide, and high purity can be obtained. Indium sulfide film.

[Embodiment 5]

First, succinic acid was used as a blocking agent, and it was dissolved in deionized water, stirred until completely dissolved, and then indium sulfate (In ₂ (SO ₄ ) ₃ ) which released indium ions was added, and stirred until completely dissolved. Then, a solution of thioacetamide (SC(NH ₂ )(CH ₃ ))) was added, and the mixture was stirred and mixed uniformly to form a mixed solution having a complexing agent, indium ions, and hydrogen sulfide ions. Among them, the concentration ratio of indium sulfide: succinic acid: thioacetamide was 0.008 M: 0.1 M: 0.4 M. The above mixed solution was placed in a reaction vessel.

Molybdenum glass was used as a substrate, and immersed in a mixed solution having a binder, indium ions, and hydrogen sulfide ions in a face down manner, and the reaction vessel was covered. The reaction was carried out for 30 minutes in a water bath at 65 ° C to obtain a yellow indium sulfide film. The coverage of the indium sulfide film on the substrate of the molybdenum glass is greater than 99%, and the film thickness thereof is about 50 to 60 nm. Referring to Fig. 8, a secondary electron image of the formed indium sulfide film is shown.

Further, the above-mentioned indium sulfide film was applied to a sputtered CIGS battery element, and its battery efficiency was tested by a method similar to that in Example 3. Among them, the obtained 2 × 2 cm 2 battery was divided into six small-area (0.38 cm 2 ) batteries, and the battery efficiency results are shown in Fig. 9. Referring to Figure 9, the optimum battery efficiency is 5.2%.

[Comparative Example 1]

First, citric acid was used as a blocking agent, and it was dissolved in deionized water, stirred until completely dissolved, and then indium sulfate (In ₂ (SO ₄ ) ₃ ) which released indium ions was added, and stirred until completely dissolved. Then, a solution of thioacetamide (SC(NH ₂ )(CH ₃ ))) was added, and the mixture was stirred and mixed uniformly to form a mixed solution having a complexing agent, indium ions, and hydrogen sulfide ions. Among them, the concentration ratio of indium sulfide: citric acid: thioacetamide is 0.008 M: 0.1 M: 0.4 M. The above mixed solution was placed in a reaction vessel.

Molybdenum glass was used as a substrate, and immersed in a mixed solution having a binder, indium ions, and hydrogen sulfide ions in a face down manner, and the reaction vessel was covered. The reaction was carried out for 30 minutes in a water bath at 65 ° C to obtain a yellow indium sulfide film having a crystalline plate shape. The coverage of the indium sulfide film on the substrate of the molybdenum glass is greater than 99%, and the film thickness thereof is about 120 to 130 nm. Referring to Fig. 10, a secondary electron image of the formed indium sulfide thin film is shown. The efficiency of applying the above indium sulfide film to sputtered CIGS battery elements was 3.4%, as shown in FIG.

[Comparative Example 2]

First, malonic acid was used as a blocking agent, and it was dissolved in deionized water, stirred until completely dissolved, and then indium sulfate (In ₂ (SO ₄ ) ₃ ) which released indium ions was added, and stirred until completely dissolved. Then, a solution of thioacetamide (SC(NH ₂ )(CH ₃ ))) was added, and the mixture was stirred and mixed uniformly to form a mixed solution having a complexing agent, indium ions, and hydrogen sulfide ions. Among them, the concentration ratio of indium sulfide: malonic acid: thioacetamide is 0.008 M: 0.1 M: 0.4 M. The above mixed solution was placed in a reaction vessel.

Molybdenum glass was used as a substrate, and immersed in a mixed solution having a binder, indium ions, and hydrogen sulfide ions in a face down manner, and the reaction vessel was covered. The reaction was carried out for 30 minutes in a water bath at 65 ° C to obtain a yellow indium sulfide film. The coverage of the indium sulfide film on the substrate of the molybdenum glass is greater than 99%, and the film thickness thereof is about 50 to 60 nm. Referring to Fig. 12, a secondary electron image of the formed indium sulfide film is shown. The efficiency of applying the above indium sulfide film to sputtered CIGS battery elements was 5.6%, as shown in FIG.

[Comparative Example 3]

Figure 14 is a comparison between Malonic acid of Comparative Example 2, Citric acid of Comparative Example 1, Succinic acid of Example 5, and Tartaric acid of Example 4, respectively. A Lehman spectrum of an indium sulfide film formed by a binder. Since succinic acid and tartaric acid are used as the wrong agent in the figure, there is no signal of indium and hydroxide bonding and indium oxide, only the signal of indium sulfide, that is, the formed indium sulfide film has no indium hydroxide or oxidation. The contamination of the substance can obtain a high-purity indium sulfide film. In the figure, when malonic acid and citric acid are used as the staggering agent, there is a signal in which indium and hydroxide are bonded, that is, the formed indium sulfide thin film is contaminated with indium hydroxide or oxide. The hydroxide of indium in the indium sulfide film affects the size of the energy gap. The higher the hydroxide content, the larger the energy gap, resulting in a mismatch with the energy level of the CIGS absorber layer, and the formation of a hetero interface (Heterointerface), resulting in structural defects, reduced penetration and increased resistance, so battery efficiency cannot be achieved. Best state.

While the invention has been described above in terms of several preferred embodiments, it is not intended to limit the scope of the present invention, and any one of ordinary skill in the art can make any changes without departing from the spirit and scope of the invention. And the scope of the present invention is defined by the scope of the appended claims.

102. . . Substrate

104. . . electrode

106. . . Absorbing layer

108. . . The buffer layer

110. . . Transparent conductive layer

Figure 1 is a cross-sectional view of a typical thin film solar cell.

Figures 2-4 are SEI diagrams of indium sulfide thin films formed in accordance with several embodiments of the present invention.

Figure 5 is a graph showing the relationship between voltage and current density of a CIGS battery formed in accordance with an embodiment of the present invention.

Fig. 6 is a SEI diagram of an indium sulfide thin film formed in accordance with an embodiment of the present invention.

Figure 7 is a diagram showing the Leyman spectrum of an indium sulfide film formed in accordance with an embodiment of the present invention.

Figures 8-13 are SEI diagrams of indium sulfide thin films formed in accordance with several comparative examples of the present invention, and the relationship between voltage and current density of the formed CIGS cells.

Fig. 14 is a diagram showing the Leyman spectrum of the formed indium sulfide thin film according to several examples and comparative examples of the present invention.

102. . . Substrate

104. . . electrode

106. . . Absorbing layer

108. . . The buffer layer

110. . . Transparent conductive layer

Claims (12)

A method for preparing an indium sulfide film, comprising: providing a mixed solution containing a binder, indium ions, and hydrogen sulfide ions; and contacting the mixed solution with a substrate to form an indium sulfide (In _{2 )} on the substrate S ₃ ) a film; wherein the complexing agent has the following chemical formula: Wherein R ₁ and R ₂ are each independently hydrogen or a hydroxyl group. The method for preparing an indium sulfide film according to claim 1, which comprises adding a metal salt containing indium to form the indium ion. The method for preparing an indium sulfide film according to claim 2, wherein the indium-containing metal salt comprises indium sulfate, indium chloride, indium acetate, or other salt soluble in water to generate indium ions, Or a combination of the foregoing. The method for preparing an indium sulfide film according to claim 1, which comprises adding thioacetamide to form the hydrogen sulfide ion. The method for producing an indium sulfide film according to claim 1, wherein the crosslinking agent comprises tartaric acid, succinic acid, or a combination thereof. The method for preparing an indium sulfide film according to claim 1, wherein the ratio of the wrong agent, the indium ion, and the hydrogen sulfide ion in the mixed solution is between 0.01 M and 0.5 M: 0.025 M to 0.1 M: 0.01 M~1 M. The method for preparing an indium sulfide film according to claim 1, wherein a reaction temperature for forming the indium sulfide film on the substrate is between 25 ° C and 80 ° C. The method for preparing an indium sulfide film according to claim 1, wherein the mixed solution has a pH of between 1 and 3. The method for preparing an indium sulfide film according to claim 1, wherein the indium sulfide film has a thickness of between 20 and 100 nm. The method for preparing an indium sulfide film according to claim 1, wherein the substrate comprises a layer of Copper Indium Gallium Diselenide (CIGS), and the indium sulfide film is formed on the copper selenide. On the indium gallium layer. The method for preparing an indium sulfide film according to claim 10, wherein the substrate further comprises an electrode layer under the copper indium gallium selenide layer. The method for preparing an indium sulfide film according to claim 11, wherein the electrode layer comprises molybdenum, gold, and/or other metal which can be used as a conductive material, and/or a combination thereof.